1. Field of the Invention
The present invention relates to a field of liquid crystal display technology, especially to a light guide plate and a corresponding backlight module that can reduce light leakage at edge sides.
2. Description of the Related Art
Liquid crystal display devices have been widely used in many kinds of electronic products. Liquid crystal display devices are mostly backlight-type liquid crystal devices that have a liquid crystal panel and a backlight module. Backlight modules are sorted into side-light type and direct-light type based on the incident position of their light sources, wherein side-light type backlight module is more used.
In order to increase the brightness of a backlight module as more as possible, designers have developed a prism light guide plate. With reference to FIG. 1, which is a structural view of a conventional side-light type backlight module having a prism light guide plate, the side-light type backlight module includes a light guide plate, a light source 12 and a fixing plastic frame 13. The light guide plate is a kind of prism light guide plate that has multiple light-exiting strip-shaped prisms 110 parallel with each other and mounted on a light-exiting surface 115 of the light guide plate. Each of the light-exiting strip-shaped prisms 110 has a cross-sectional direction X that is basically parallel with an incident surface 112 of the light guide plate. The light source 12 generally is an LED light bar. The fixing plastic frame 13 is used to fix the light guide plate. After lights of the light source 12 are transmitted into the light guide plate from the incident surface 112, the lights that propagate along an extension direction Y (which is basically perpendicular to the incident surface 112 of the light guide plate) of the light-exiting strip-shaped prisms 110 may have a longer propagation distance due to total internal reflection; and the lights that propagate along the cross-sectional direction X of the light-exiting strip-shaped prisms 110 may have a shorter propagation distance because total internal reflection does not easily occur and therefore it performs a certain converging effect for the lights of the light source 12 and enhances the work efficiency of the light source 12.
With reference to FIGS. 2A and 2B, FIG. 2A is a top view of the conventional side-light type backlight module having a prism light guide plate and FIG. 2B is a cross-sectional view taken along the line A-A in FIG. 2A. Because of the existence of the light-exiting strip-shaped prisms 110 of the light guide plate, total refection may not occur for the lights which have already been reflected by sides 113 of the light guide plate due to the structure of the light-exiting strip-shaped prisms 110, and thereby cause light leakage B1 and B2 to occur at the junction between the light guide plate and the fixing plastic frame 13 and then affect the display quality of its corresponding liquid crystal display device.
Hence, it is necessary to provide a light guide plate and a corresponding backlight module to overcome the problems existing in the conventional technology.